Electronic devices like cellular phones, tablets, computers, radios, bar code scanners and hearing aids may have at least one acoustic transducer to convert electrical signals into sound or vice-versa. Acoustic transducers such as loudspeakers, microphones, ringers, buzzers, etc. are placed in a protective housing with one or more small apertures which enable sound transmission and reception. These apertures are typically covered with an acoustic cover assembly to protect the transducer from particulate and or liquid contaminants present in the ambient environment. To preserve acoustic performance of transducers, such acoustic covers must provide minimal sound attenuation.
Acoustic cover assemblies may include cover materials such as micro-porous membranes, non-porous films and porous fabrics including both woven and non-woven materials. These cover materials are usually used in conjunction with a gasket which serves to seal and focus acoustic energy to the apertures and prevent any sound leakage.
Known acoustic protective cover assemblies are described in U.S. Pat. No. 6,932,187, U.S. Pat. No. 6,512,834, U.S. Pat. No. 5,828,012 and US 2010/0270102. In use, the gasket in an acoustic cover assembly may be compressed to about 50% of its original thickness when installed in an electronic device. Compression of the gasket facilitates a good seal between the assembly and the components of the device. However, gasket compression may effect the cover material tension, which may in turn alter the acoustic performance. If a cover material has higher tension as a result of gasket compression, it can cause sound waves to reflect off the cover material. The effect would be a higher acoustic insertion loss for the cover material, ultimately degrading the frequency response of the acoustic system.
Therefore, there still exists a need to provide an improved acoustic cover assembly which has minimal acoustic insertion loss under compression while offering a high level of protection from external contaminants.